WO2008004557A1

WO2008004557A1 - Branch circuit, high frequency circuit and high frequency module

Info

Publication number: WO2008004557A1
Application number: PCT/JP2007/063323
Authority: WO
Inventors: Kenji Hayashi; Masayuki Uchida
Original assignee: Hitachi Metals, Ltd.
Priority date: 2006-07-03
Filing date: 2007-07-03
Publication date: 2008-01-10
Also published as: US20090295501A1; EP2040377B1; KR101404535B1; CN101485085B; KR20090035480A; CN101485085A; TWI420834B; JP5463669B2; KR101421452B1; EP2040377A1; WO2008004557B1; JP5569571B2; EP2040377A4; JPWO2008004557A1; JP2013048448A; KR20140043508A; US8183956B2; TW200816664A

Abstract

A branch circuit is provided with a common terminal, a low frequency terminal, a high frequency terminal, a low frequency side path having a low frequency filter arranged between the common terminal and the low frequency terminal, and a high frequency side path having a high frequency filter arranged between the common terminal and the high frequency terminal. The low frequency filter is provided with a first transmission line connected in series to the low frequency side path, and a capacitor connected in parallel to a part of the first transmission line.

Description

Specification

Demultiplexing circuit, high frequency circuit and high frequency module

Technical field

TECHNICAL FIELD [0001] The present invention relates to a demultiplexing circuit, a high-frequency circuit, and a high-frequency module using the demultiplexing circuit used in a communication device such as a wireless communication device between mobile communication devices such as mobile phones, electronic devices, and electric devices. .

Background art

[0002] For example, EGSM (Extended Global System for Mobile Communications) method and DCS (Digital Cellular System) method popular in Europe, PCS (Personal Communication Service) method popular in the United States, There are various systems using time division multiple access (TDMA) such as PDC (Personal Digital Cellular). Conventionally, as a compact and lightweight high-frequency circuit component compatible with multiple systems, for example, a dual-band compatible high-frequency switch module used in portable communication devices compatible with two systems of EGSM and DCS, and three types of EGSM, DCS, and PCS A triple-band compatible high-frequency switch module, etc., used for portable communication devices compatible with the system has been proposed. Currently, data communication by wireless LAN represented by the IEEE802.il standard is widely used, but there are a plurality of standards with different frequency bands in this wireless LAN standard. Various high-frequency circuits are also used in multiband communication devices using wireless LAN.

[0003] When a single mobile phone is shared by a plurality of frequency bands, a high-frequency switch module incorporating a circuit for demultiplexing transmission / reception signals of a plurality of frequency bands transmitted / received by an antenna and a switch for switching transmission / reception paths is provided. is necessary. High-frequency switch modules, which are key parts of multiband wireless communication, are increasingly required to be smaller and have higher performance. In particular, it is essential to remove unwanted band noise.

[0004] In order to meet such a requirement, Japanese Patent Application Laid-Open No. 11-27177 uses a stray capacitance generated between the antenna and the ground in order to eliminate harmonic distortion generated in the transmission signal from the power amplifier. A high-frequency switch with a reduced number of filters is proposed. This high frequency switch Tsuchi adjusts the stray capacitance generated between the antenna terminal, the transmitter circuit terminal and the receiver circuit terminal and the ground, and adjusts the length of the transmission line, which is a choke element, to approximately / 6. An attenuation pole is provided in the harmonic band. Although a specific adjustment method is not described, it is very troublesome to adjust all of these stray capacitances and at the same time adjust the transmission line to a desired length. For example, in a GSM system, it is necessary to reduce the harmonic level up to about 7th harmonic. Since this method uses only the 3rd harmonic attenuation pole, this higher harmonic level is reduced. Can not ,.

[0005] Japanese Patent Laid-Open No. 2003-69362 proposes a diplexer in which a parallel resonant circuit having a resonance frequency of the second harmonic is provided on the low-pass filter terminal side in order to efficiently remove the second harmonic. ing. In this diplexer, by providing parallel resonance circuits at the common terminal and low-pass filter terminal, signal loss is reduced and harmonics twice the first frequency on the low frequency side are efficiently removed. Specifically, the low-pass filter circuit of the diplexer has two parallel resonance circuits composed of a coil and a capacitor, and a grounding capacitor is provided at the connection portion of these parallel resonance circuits and the low-pass filter terminal. . However, if two parallel resonant circuits are connected, the circuit configuration becomes complicated as well as the diplexer becomes larger. In addition, multi-stage low-pass filters have a large insertion loss, which has a detrimental effect on characteristics. In addition, the low-pass filter circuit of this diplexer is set to attenuate the second frequency or twice the first frequency, so that unnecessary bands other than the nth harmonic cannot be sufficiently reduced.

[0006] EGSM and DCS use frequency bands different from the 900 MHz band and 1800 MHz band, respectively, but if both circuits are mixed, the signal leaks and the isolation characteristics deteriorate. This problem becomes apparent as the high frequency components become smaller. On the other hand, Japanese Patent Laid-Open No. 20 01-352202 divides a region in the plane direction of a laminate in one high-frequency switch module that handles a plurality of transmission / reception systems having different passbands. A high-frequency switch module is proposed. However, since different regions are formed separately in the plane direction of the laminate, there is a problem that one transmission / reception system and the other transmission / reception system cannot be shielded sufficiently.

[0007] Japanese Patent Application Laid-Open No. 2004-3281 relates to a low-pass filter used in a high-frequency switch module No. 36 is a low-pass filter in which a series resonance circuit and a parallel resonance circuit are cascaded in order to improve the attenuation characteristics of the second harmonic and the third harmonic of the signal wave (fundamental wave). A low-pass filter is proposed in which a grounding capacitor is connected to both ends, and a phase-adjustment transmission line is interposed between the series resonant circuit and the parallel resonant circuit. However, the attenuation characteristics and insertion loss of this low-pass filter were not always sufficient in response to the demand for higher performance due to the multiband and the like. If a low-pass filter and a notch filter are combined into a composite filter and a transmission line connecting them is added, characteristic degradation due to electromagnetic interference between circuits, transmission lines constituting the filter, and capacitance, and parasitic capacitance is reduced. Occur. In addition, the composite filter sacrifices downsizing to improve characteristics. In this way, with the progress of high integration of multilayer modules, the layout of low-pass filters and inductors and other elements that constitute multilayer modules using the same should be designed while satisfying the demands for miniaturization and high performance. Was difficult. Disclosure of the invention

Problems to be solved by the invention

[0008] Therefore, a first object of the present invention is to provide a branching circuit that reduces the unnecessary band while suppressing the complexity and size of the circuit and the increase in insertion loss.

[0009] A second object of the present invention is to provide a high-frequency circuit including such a branching circuit.

A third object of the present invention is to provide a high frequency module in which such a high frequency circuit is configured on a multilayer substrate.

A fourth object of the present invention is to provide a high-frequency joule that suppresses mutual interference and signal leakage between transmission / reception circuits having different frequency bands while suppressing an increase in mounting area.

A fifth object of the present invention is to provide a high-frequency module having a low-pass filter that is easy to design an inductor and a capacitor and has excellent filter performance.

Means for solving the problem

[0013] A first branching circuit of the present invention includes a common terminal, a low frequency terminal, a high frequency terminal, and a low frequency filter having a low frequency filter provided between the common terminal and the low frequency terminal. Side path And a high-frequency side path having a high-frequency filter provided between the common terminal and the high-frequency terminal, the low-frequency filter being connected in series to the low-frequency side path And a capacitor connected in parallel to a part of the first transmission line. In this branching circuit, the parallel resonant circuit that suppresses the unnecessary band is configured by using a part of the first transmission line on the low frequency side path, so that the branching circuit can be reduced in size.

[0014] In the branching circuit, the capacitor is connected in parallel to a part on the low frequency terminal side of the first transmission line to form a parallel resonant circuit, and the part other than the part of the first transmission line. It is preferable that this part constitutes an inductance part. Of the first transmission line of the low frequency filter, the portion constituting the inductance portion is arranged on the common terminal side, and the portion constituting the parallel resonance circuit is arranged on the low frequency terminal side, thereby arranging the parallel resonance circuit. The degree of freedom increases. One end of the capacitor may be connected in parallel to a part of the first transmission line, and the other end may be connected to another circuit element connected to the low frequency terminal.

[0015] A second branching circuit of the present invention includes a common terminal, a low-frequency terminal, a high-frequency terminal, and a low-frequency filter having a low-frequency filter provided between the common terminal and the low-frequency terminal. A capacitor having a side path and a high-frequency side path having a high-frequency filter provided between the common terminal and the high-frequency terminal, and a parasitic capacitance formed on the common terminal side for suppressing unnecessary waves; It is characterized by doing. If the common terminal of this branching circuit is connected to other circuit elements, the parasitic capacitance functions as a capacitive element, and the design efficiency and flexibility are improved. For example, when the common terminal is connected to an antenna, the parasitic capacitance can be added to the antenna terminal, which is effective in suppressing harmonics.

[0016] In the branching circuit, the high frequency filter may include a first capacitor connected to the common terminal, and the parasitic capacitance may be formed on the common terminal side of the first capacitor.

[0017] In the branching circuit, an electrode connected to the common terminal among the counter electrodes constituting the first capacitor and a ground electrode are arranged to face each other, and thus the parasitic is interposed between the two electrodes. It is preferable that the capacity is formed. By using the electrode on the connection terminal side of the capacitor connected to the common terminal of the capacitors that make up the demultiplexing circuit, With such a structure, parasitic capacitance can be formed efficiently, so that an increase in circuit size can be avoided.

[0018] In the branching circuit, the high-frequency filter includes a first capacitor connected to the common terminal, a second capacitor connected between the first capacitor and the high-frequency terminal, A third transmission line connected between the first capacitor and the second capacitor and the ground, and a series resonance circuit consisting of a third capacitor, the third transmission line, The one capacitor, the second capacitor, and the third capacitor are configured in a stacked body in which dielectric layers having electrode patterns are stacked, and the first capacitor is configured in the stacked body. It is preferable that the electrode connected to the common terminal is opposed to the ground electrode. Since the electrode connected to the common terminal among the capacitors constituting the branching circuit is opposed to the ground electrode, the area of the ground electrode that can efficiently generate parasitic capacitance and the first capacitor The parasitic capacitance can be easily adjusted by changing the distance between the electrode connected to the common terminal and the ground electrode among the counter electrodes constituting the.

[0019] A first high-frequency circuit of the present invention includes the first branching circuit, includes a second transmission line connected to the low-frequency terminal, and the capacitor includes the first transmission line. A part and at least a part of the second transmission line are connected in parallel. Since the parallel resonance circuit that suppresses the unnecessary band is configured by using the first transmission line and the transmission line of another circuit connected to the low frequency terminal, the branching circuit can be reduced in size. Further, since the capacitor is connected so as to straddle the first transmission line and the second transmission line, the capacitor can be easily arranged when the high-frequency circuit is formed on the multilayer substrate.

[0020] The high-frequency circuit includes a switch circuit that is connected to the low-frequency terminal and switches between the transmission-side path and the reception-side path of the low-frequency side path, and the second transmission line is the switch It is preferable that the transmission line is provided in the circuit on the receiving side. With this configuration, a small high-frequency circuit that has a switch circuit in the subsequent stage of the branching circuit and suppresses unnecessary bands can be obtained.

[0021] In the first high-frequency module of the present invention, the branching circuit or the high-frequency circuit is configured on a multilayer substrate formed by laminating dielectric layers on which electrode patterns are formed. Features. With this configuration, a small high-frequency circuit that suppresses unnecessary bands can be obtained.

[0022] In the above high-frequency module, an electrode pattern constituting a part of the first transmission line, an electrode pattern constituting at least a part of the second transmission line, and an electrode pattern of the capacitor are formed of a laminate. Overlapping in the stacking direction! / This configuration can reduce the size of the parallel resonant circuit and is advantageous for downsizing the high-frequency module.

[0023] The second high-frequency module of the present invention is characterized in that the second demultiplexing circuit is configured on a multilayer substrate formed by laminating dielectric layers in which electrode patterns are formed. If the common terminal of this demultiplexing circuit is connected to other circuit elements, the parasitic capacitance functions as a capacitive element, and the design efficiency and flexibility of the high-frequency module is improved.

[0024] The high frequency module includes a first switch circuit that switches between a transmission system and a reception system in a first frequency band divided by the branching circuit, and a transmission in a second frequency band divided by the branching circuit. It is preferable to have a second switch circuit that switches between the system and the receiving system. When the demultiplexing circuit of the high-frequency antenna switch module having a powerful structure is connected to the antenna, the parasitic capacitance generated in the demultiplexing circuit can be added to the antenna terminal, and harmonics are suppressed.

[0025] A third high-frequency module of the present invention is used for a multiband radio communication device that selectively uses at least a first frequency band and a second frequency band higher than the first frequency band. A demultiplexing circuit that separates a first transmission / reception system in the first frequency band and a second transmission / reception system in the second frequency band; and a transmission system connected to the demultiplexing circuit and connected to the first transmission / reception system And a first switch circuit for switching the reception system, and a second switch circuit connected to the branching circuit and for switching the transmission system and the reception system of the second transmission / reception system, the branching circuit, The first switch circuit and the second switch circuit are configured as a laminate formed by laminating dielectric layers on which electrode patterns are formed, and the branching circuit, the first switch circuit, and the second switch circuit are formed. Switch times The transmission line through which the signal in the first frequency band passes is formed on one side in the stacking direction of the ground electrode provided in the dielectric layer in the stack, A transmission line through which a signal in a frequency band passes is formed on the other side in the stacking direction of the ground electrode. [0026] Since the transmission line through which the signal in the first frequency band and the transmission line through which the signal in the second frequency band have are separated in the stacking direction by the ground electrode, It is possible to suppress mutual interference and leakage of signals and unwanted harmonics. Since the transmission line through which the signal in the first frequency band passes and the transmission line through which the signal in the second frequency band pass are separated in the stacking direction, the plane dimension increases due to the separation of both circuits. Can be avoided.

[0027] In addition to the first and second frequency bands, a transmission / reception circuit for a third frequency band or the like having a different frequency band may be provided. In this case, it is preferable that transmission lines through which signals in the third or fourth frequency band pass are formed collectively on one side of the ground electrode.

[0028] In the third high-frequency module, it is preferable that the second frequency band and the frequency band of the second harmonic of the first frequency band are substantially the same. If the frequency band of the second frequency band and the double frequency band of the first frequency band are the same, the leakage of unwanted harmonics in the first frequency band has a significant effect on the signal in the second frequency band. Therefore, the third high-frequency module that reliably shields the first frequency band and the second frequency band is particularly effective.

[0029] The third high-frequency module includes a low-pass filter including a transmission line that forms an inductance and a capacitor in order to suppress harmonics, and an electrode pattern that forms the transmission line is formed. The dielectric layer on which the electrode pattern constituting the capacitor is formed is separated in the laminating direction by a ground electrode, and the direction in which the ground electrode is laminated with respect to the electrode pattern constituting the transmission line It is preferable not to have a ground electrode facing the opposite side. In this case, one side of the ground electrode in the stacking direction is an inductance forming part, and the other side is a capacitor forming part. In this configuration, since the ground electrode is disposed between the transmission line and the capacitor, interference between the transmission line and the capacitor is prevented, the filter performance is improved, and the transmission line and the capacitor are easily designed.

[0030] Preferably, the third high-frequency module does not include a ground electrode facing the opposite side of the ground electrode in the stacking direction with respect to the electrode pattern constituting the capacitor. According to this configuration, the low-pass filter can be reduced in size. [0031] The high-frequency module preferably includes a plurality of the capacitors. In the case of having a plurality of capacitors such as a π-type or ladder-type low-pass filter, interference is likely to occur if the capacitors are arranged close to the inductance. On the other hand, by forming the plurality of capacitors together on one side in the stacking direction of the ground electrode, interference between the transmission line forming the inductance and the capacitor can be effectively suppressed. There may be a plurality of transmission lines forming an inductance, such as a ladder-type low-pass filter. In this case, the transmission line is formed collectively on the opposite side of the capacitor with respect to the ground electrode.

[0032] In the high-frequency module, at least one of the capacitors may be connected in parallel to the transmission line. Even with this configuration, the interference between the transmission line and the capacitor is effectively suppressed.

The invention's effect

[0033] The branching circuit of the present invention includes a first transmission line in which a low-frequency filter is connected in series to the low-frequency side path, and a capacitor connected in parallel to a part of the first transmission line. Therefore, the unnecessary band can be effectively suppressed while being small in size and low loss. The high-frequency module of the present invention can suppress signal leakage and interference between transmission / reception systems having different frequency bands while maintaining a small size.

Brief Description of Drawings

FIG. 1 is a diagram showing an equivalent circuit of a branching circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of a high-frequency circuit according to another embodiment of the present invention.

FIG. 3 is a diagram showing an equivalent circuit of the quad-band antenna switch circuit of the present invention.

FIG. 4 is a partial development view showing an electrode layer with an electrode pattern constituting the high-frequency module according to one embodiment of the present invention.

FIG. 5 is a graph showing pass characteristics of a high-frequency module according to an embodiment of the present invention.

FIG. 6 is a graph showing pass characteristics of a high-frequency switch module of a comparative example.

FIG. 7 is a diagram showing an equivalent circuit of a branching circuit according to another embodiment of the present invention.

FIG. 8 is a diagram showing parasitic capacitance in an equivalent circuit of a branching circuit according to another embodiment of the present invention.

FIG. 9 schematically shows a part of a laminate of a high-frequency module according to another embodiment of the present invention. FIG.

FIG. 10 is a diagram showing an equivalent circuit of a quad-band antenna switch circuit according to another embodiment of the present invention.

FIG. 11 is a block diagram showing a high-frequency module according to still another embodiment of the present invention.

FIG. 12 is a partial development view showing a dielectric layer with an electrode pattern constituting a high-frequency module according to still another embodiment of the present invention.

FIG. 13 is a partial development view showing a dielectric layer with an electrode pattern constituting still another high-frequency switch module of the present invention.

FIG. 14 is a partial development view showing a dielectric layer with an electrode pattern constituting a laminated high-frequency module using a low-pass filter according to an embodiment of the present invention.

FIG. 15 is a diagram showing an equivalent circuit of a low-pass filter according to one embodiment of the present invention.

FIG. 16 is a diagram showing an equivalent circuit of a low-pass filter according to another embodiment of the present invention.

FIG. 17 (a) is a cross-sectional view schematically showing an example of a low-pass filter used in the present invention.

FIG. 17 (b) is a cross-sectional view schematically showing another example of the low-pass filter used in the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0035] [1] First embodiment

(A) Demultiplexer circuit

FIG. 1 shows an equivalent circuit of a branching circuit according to an embodiment of the present invention. The demultiplexing circuit passes the transmission signal of the high-frequency side transmission circuit or the low-frequency side transmission circuit during transmission, and demultiplexes the reception signals with different frequencies during reception to the high-frequency side reception circuit or low-frequency side reception circuit. Has the function of distributing. The branching circuit shown in FIG. 1 has a common terminal Pc, a low-frequency terminal PI, and a high-frequency terminal Ph, and has a low-frequency filter and a high-frequency filter, and signals connected to the common terminal Pc using these filters. The path is branched into a low-frequency path that connects the common terminal Pc and the low-frequency terminal P1, and a high-frequency path that connects the common terminal Pc and the high-frequency terminal Ph.

[0036] The low frequency filter has one end connected between the first transmission line LL1 provided between the common terminal Pc and the low frequency terminal P1, and between the first transmission line LL1 and the low frequency terminal P1. The other end is grounded The transmission line LL2 is composed of a series resonant circuit of the first capacitor CL1. By setting the resonance frequency of the series resonance circuit of the transmission line LL2 and the first capacitor CL1 to be the same as the signal frequency on the high frequency side, for example, it is possible to prevent the high frequency side signal from wrapping around to the low frequency side. In this embodiment, a capacitor C is connected in parallel to a part of the first transmission line LL1 (low frequency terminal P1 side) of the low frequency filter, thereby forming a parallel resonance circuit. The remaining part of the first transmission line LL1 (common terminal Pc side) constitutes an inductor. Since part of the first transmission line LL1 forms a parallel resonant circuit with the capacitor C, it is possible to avoid an increase in the size of the low frequency filter circuit due to the addition of the parallel resonant circuit. In the example shown in FIG. 1, the capacitor C is connected in parallel with a part of the first transmission line LL1, not limited to this configuration, and the capacitor C is another circuit connected in series with the first transmission line LL1. It may be connected in parallel to the part including the element. Except for the series resonant circuit and the parallel resonant circuit of a part of the first transmission line LL1 and the capacitor C, the configuration is not limited to that shown in FIG.

[0037] The high frequency filter includes the second and third capacitors CH4 and CH5 connected between the common terminal Pc and the high frequency terminal Ph, and the connection point between the second and third capacitors CH4 and CH5 and the ground. A series resonance circuit including a transmission line LH4 and a fourth capacitor CH6 connected between them. However, the circuit configuration of the high-frequency filter is not limited to this configuration, and can be changed as appropriate.

[0038] A branching circuit having a configuration in which a part of the first transmission line LL1 and the capacitor C are connected in parallel can be configured as follows in a multilayer substrate including a dielectric layer having an electrode pattern. For example, the electrode pattern of the capacitor C is formed on the adjacent dielectric layer so as to face a part of the electrode pattern of the first transmission line LL1 formed on the dielectric layer, and one end of these electrode patterns is formed. To the low frequency terminal P1. The width of a part of the first transmission line LL1 may be made larger than the other part.

[0039] (B) High frequency circuit

FIG. 2 shows an equivalent circuit of a high-frequency circuit according to an embodiment of the present invention. This high-frequency circuit includes a demultiplexing circuit and has a second transmission line Lg2 provided in a subsequent circuit connected to the low-frequency terminal P1 of the demultiplexing circuit, and the low-frequency of the first transmission line LL1. Terminal P1 side A capacitor is connected in parallel to a part and at least a part of the second transmission line Lg2 on the low frequency terminal PI side. In the example shown in FIG. 2, the subsequent circuit is a switch circuit (circuit configuration will be described later) that switches between the transmission side path and the reception side path of the low frequency side path. The second transmission line Lg2 is provided in the receiving side path of the switch circuit. Figure 2 also shows the diode Dgl of the switch circuit connected to the low frequency terminal P1.

[0040] Thus, the first transmission line LL1 of the low-frequency filter of the branching circuit, the second transmission line Lg2 provided in the receiving side path of the switch circuit, and the capacitor C connected in parallel to these Since the parallel resonant circuit is configured as described above, the circuit does not increase in size. By adjusting the resonant frequency of this parallel resonant circuit to a band other than the frequency of the received signal, it is possible to widely attenuate the unnecessary band. The other circuit configurations such as the high frequency filter are the same as those shown in FIG. The capacitor C may be connected in parallel with a part of the second transmission line Lg2, or may be connected in parallel with the entire second transmission line Lg2.

[0041] The high-frequency circuit shown in FIG. 2 can be configured as a high-frequency module by forming it on a multilayer substrate having a dielectric layer force on which an electrode pattern is formed. Examples of the high-frequency module include an antenna switch module that switches a signal path between a transmission system and a reception system connected to an antenna, a high-frequency amplifier module that includes a high-frequency amplifier circuit that amplifies a transmission signal, and the antenna switch module. Examples of the integrated module include, but are not limited to.

As a high-frequency module according to an embodiment of the present invention, FIG. 3 shows a low-frequency GSM850 band (transmission frequency: 824 to 849 MHz, reception frequency: 869 to 894 MHz) and an EGSM band (transmission frequency: 880 to 915 MHz, reception frequency: 925 to 960 MHz), and high frequency DCS band (transmission frequency: 1710 to 1785 MHz, reception frequency: 1805 to 1880 MHz) and PCS band (transmission frequency: 1850 to 1910 MHz, An equivalent circuit of a quad-band antenna switch circuit using a reception frequency of 1930 to 1990 MHz) is shown. This antenna switch circuit is disposed after the demultiplexing circuit Dip, which is a low-frequency filter and a high-frequency filter power, and the low-frequency filter of the demultiplexing circuit. The first switch circuit SW1 that switches between terminals Rx-LB and the high-frequency filter of the demultiplexing circuit And a second switch circuit SW2 that switches between the transmission terminal Tx-HB and the reception terminal Rx-HB by a voltage supplied from the control terminal Vc. The low frequency transmission terminal Tx-LB and the reception terminal Rx-LB are shared by GSM and EGSM, and the high frequency transmission terminal Tx-HB and the reception terminal Rx-HB are shared by DCS and PCS. . The low-frequency side receiving terminal Rx-LB and the high-frequency side receiving terminal Rx-HB are selectively used depending on the region where the mobile terminal in which this module is installed is used. For example, in Europe, Rx-LB is used as EGSM, Rx. -HB is assigned to DCS. In the US, Rx-LB is assigned to GSM and Rx-HB is assigned to PCS. At this time, each transmitter / receiver terminal needs to have a broadband design with desired characteristics in the GSM850 and EGSM bands, which are low frequency bands, and the DCS and PCS bands, which are high frequency bands. Further, a low-frequency receiving terminal Rx-LB and a high-frequency receiving terminal Rx-HB may be followed by a switch circuit (not shown) and provided with four receiving terminals.

[0043] The high frequency module is not limited to the quad band, and may be a triple band or dual band high frequency switch module. For example, one of the low frequency band GSM850 and EGSM may be the first frequency band, and one of the high frequency band DCS and PCS may be the second frequency band. Furthermore, the high-frequency module is not limited to a mobile phone communication system, but may be used for another communication system such as a wireless LAN. The number and arrangement of circuit elements such as filter circuits, switch circuits, detector circuits, balanced / unbalanced circuits, etc. used in the high-frequency circuit and the high-frequency module may be changed as necessary.

In the antenna switch circuit shown in FIG. 3, a branching circuit (diplexer) Dip composed of a low-frequency filter and a high-frequency filter is used to separate the transmission / reception system in the first frequency band from the transmission / reception system in the second frequency band. A low-pass filter is provided as a low-frequency filter (GSMZEGSM Side) that passes the GSM and EGSM transmission and reception signals and attenuates the DCS and PCS transmission and reception signals, and passes the GSM and EGSM transmission signals. A high-pass filter is provided as a high-frequency (DCSZPCS Side) filter that attenuates the transmitted and received signals. The low-frequency filter and high-frequency filter connected to the antenna terminal Ant, which is a common terminal, are each composed of a transmission line and a capacitor! However, they can also be composed of a band-pass filter or a notch filter.

[0045] In a low-pass filter as a low frequency side (GSMZEGSM Side) filter, a transmission line Route LL1 has a high impedance to the signal in the high frequency band (DCS and PCS) that allows low frequency band (GSM and EGSM) signals to pass through with low loss, and prevents the DCS and PCS band signals from wrapping around. The transmission line LL1 is preferably set to a length that provides high impedance at the frequency of the DCS and PCS band signals so that signals in the DCS and PCS bands are not transmitted to the GSM system path. Transmission line LL2 and capacitor CL1 form a series resonant circuit with resonant frequencies in the DCS and PCS bands, and drop signals in the DCS and PCS bands to ground to prevent wraparound. In a high-pass filter as a high-frequency side (DCSZPCS Side) filter, capacitors CH4 and CH5 allow high-frequency band (DCS and PCS) signals to pass through with low loss, but for low-frequency band (GSM and EGSM) signals. High impedance prevents wraparound of GSM and EGSM band signals. The transmission line LH4 and the capacitor CH4 constitute a series resonance circuit having a resonance frequency in the GSM and EGSM bands, and drop signals in the GSM and EGSM bands to the ground to prevent wraparound.

The switch circuit shown in FIG. 3 is connected to the branching circuit and is connected to the first transmission / reception system.

The first switch circuit SW1 that switches between the (transmission terminal Tx-LB) and the reception system (reception terminal Rx-LB), and the second transmission / reception system transmission system (transmission terminal Tx-HB) connected to the demultiplexing circuit And a second switch circuit SW2 for switching the receiving system (receiving terminal Rx-HB). The first and second switch circuits SW1 and SW2 have a switch element and a transmission line as main elements. As the switch element, a force GaAs switch for which a PIN diode is suitable can be used. Switch circuits using PIN diodes are less expensive than switch circuits using GaAs switches. GaAs switches can consume less power than switch circuits using PIN diodes. select.

[0047] The first switch circuit SW1 (in the upper part of Fig. 3) that switches between the transmitting terminal Tx-LB and the receiving terminal Rx-LB of GSMZEGSM mainly consists of two diodes Dgl and Dg2 and two transmission lines Lgl and Lg2. Element. The diode Dgl is inserted between the low frequency filter of the demultiplexing circuit and the transmission terminal Tx-LB, the anode of the diode Dgl is connected to the low frequency filter of the demultiplexing circuit, and the power sword of the diode Dgl is transmitted It is connected to an L-type low-pass filter LPF1 composed of line LL3 and capacitors CL2 and CL3. A transmission line Lgl is connected between the other end of the transmission line LL3 constituting the low-pass filter LPF1 and the ground. Rover The filter LPF1 passes the GSMZEGSM transmission signal in order to suppress high-order harmonic distortion contained in the transmission signal input from the power amplifier (not shown) on the GSMZEGSM side, but it is twice the GSMZEGSM transmission signal. It is preferable to have a characteristic that sufficiently attenuates the above frequencies. Power amplifier force In order to sufficiently attenuate the harmonic distortion contained in the input GSMZEGSM transmission signal, the transmission line LL3 and capacitor CL3 that form an inductance have a resonance frequency that is twice or three times the transmission frequency of GSMZEGSM. A parallel resonance circuit is configured.

[0048] The capacitors Cg6, Cg2, and Cgl function as a DC cut capacitor that removes the DC component and applies a control DC voltage to the circuit including the diodes Dgl and Dg2, and also functions as a part of the phase adjustment circuit. Function. A transmission line Lg2 is inserted between the anode of the diode Dgl and the receiving terminal Rx-LB. The diode Dg2 is connected between one end of the transmission line Lg2 and the ground, and between the anode of the diode Dg2 and the ground. Capacitor Cgl is connected. A resistor Rg is connected in series between the anode of the diode Dg2 and the control terminal Vc. The capacitor Cvg connected between the control terminal Vc and the ground prevents noise from entering the control power supply and stabilizes the control. The transmission line Lgl and the transmission line Lg2 are λ / 4 lines, and preferably both have a line length such that the resonance frequency is within the frequency band of the transmission signal of GSMZEGSM. For example, if each resonance frequency is set to a frequency (869.5 MHz) approximately in the middle of the GSM transmission signal frequency, excellent insertion loss characteristics can be obtained within the desired frequency band.

[0049] The second switch circuit SW2 (in the lower part of Fig. 3) switches between the reception terminal Rx-HB common to DCS and PCS and the transmission terminal Tx-HB common to DCS and PCS. The second switch circuit SW2 includes two diodes Ddl and Dd2 and two transmission lines Ldl and Ld2 as main elements. The diode Ddl is inserted between the high frequency filter of the branching circuit and the transmission terminal Tx-HB, the anode of the diode Ddl is connected to the high frequency filter of the branching circuit, and the power sword of the diode Ddl is composed of the transmission line LH5 and the capacitor. Connected to L-type lowpass filter LPF2 composed of CH7 and CH8. A transmission line Ldl is connected between the other end of the transmission line LH5 constituting the low-pass filter LPF2 and the ground. The low-pass filter LPF2 is a high-order filter included in the transmission signal input from the DCS and PCS side power amplifiers (not shown). In order to suppress harmonic distortion, it is preferable that the DCS or PCS transmission signal has a characteristic that sufficiently attenuates a frequency that is at least twice that of the DCS or PCS transmission signal. In order to ensure isolation between the transmitting terminal Tx-HB and the antenna terminal Ant and between the transmitting terminal Tx-- and the receiving terminal Rx-HB when the diode Ddl is OFF, the inductor Ls and the capacitor Cs are connected in series. A circuit is connected in parallel with the diode Ddl to cancel the capacitance component of the diode when OFF.

[0050] The transmission lines Ldl and Ld2 are λΖ4 lines, both of which preferably have a line length that falls within the frequency band of the transmission signal of the transmission / reception system of the resonance frequency force ¾CS and PCS, particularly the frequency It is preferable to have a line length that is an intermediate frequency in the band. For example, if the resonance frequency of the transmission lines Ldl and Ld2 is set to a frequency (1810 MHz) approximately halfway between the transmission signals in the DCS band and the PCS band, excellent electrical characteristics can be obtained in each mode. The signal can be handled by one circuit. The capacitor Cd2 functions as a DC cut capacitor that removes the DC component and applies a control DC voltage to the circuit including the diodes Ddl and Dd2, and also functions as a part of the phase adjustment circuit. One end of the transmission line Ld2 is connected to the capacitor CH5 constituting the high-frequency filter of the branching circuit, and the other end of the transmission line Ld2 is connected to the diode Dd2 and the capacitor Cdl connected to the ground. The control terminal Vc is connected to the anode of the diode Dd2 via the resistor Rd. Capacitor Cvd stabilizes control by preventing noise from entering the control power supply. Capacitor Cd5 is a DC cut capacitor.

[0051] Inductor L1 functions to prevent destruction of the module when an overcurrent is applied to the antenna terminal due to static electricity, lightning strikes, etc., to ground GND. Inductors L2 and Cg2 and inductors L5 and Cd2 function as a high-pass phase adjustment circuit that adjusts the connection phase, respectively, and suppress harmonics that leak from the high-frequency amplifier circuit HPA. The relationship with the antenna switch side impedance is adjusted so that it becomes conjugate matching for the fundamental wave and non-conjugated matching for the unnecessary n-th harmonic wave. L3, C2, L4, and CI constitute an LC resonant circuit and an LC high-pass circuit, and have a resonance point near 250 MHz to attenuate electrostatic pulses and prevent leakage of electrostatic pulses to the back of the receiving terminal. , Preventing the destruction of the bandpass filter behind. C3 is a matching adjustment capacitor. [0052] (C) High frequency module

Fig. 4 shows a high-frequency module in which the antenna switch circuit shown in Fig. 3 is formed on an 11-layer multilayer board. BOTTOM indicates the back side of the multilayer substrate. An antenna switch circuit is formed in the region 1 of about 1/3 on the right side of each layer, and a high-frequency amplifier circuit (not shown) is formed in the region 2 of about 2/3 on the left side. The branching circuit has the configuration shown in FIG. The high-frequency amplifier circuit is connected to the transmission terminal Tx-LB of the GSMZEGSM of the antenna switch circuit, for example, and sends the amplified transmission signal to the antenna switch circuit. It is preferable that the connection between the high-frequency amplifier and the antenna switch circuit is provided on the upper layer side, and the line of the high-frequency amplifier and the line of the antenna switch circuit are formed in different layers so as not to overlap each other in order to avoid mutual interference.

In FIG. 4, the electrode patterns corresponding to the transmission lines and capacitors shown in FIGS. 2 and 3 are denoted by the same reference numerals. The second capacitor CH4 and third capacitor CH5 of the high frequency filter of the branching circuit and the first capacitor CL1 of the low frequency filter are provided below the sixth dielectric layer provided with the ground electrode. . The electrode patterns of the transmission line LL2 and the first capacitor CL1 constituting the series resonant circuit are formed so as to overlap in the stacking direction. Similarly, the electrode patterns of the transmission line LH4 and the fourth capacitor CH6 constituting the series resonant circuit are formed so as to overlap in the stacking direction. The electrode pattern of the first transmission line LL1 of the low-frequency filter is formed on the second to fifth layers so as to form a coil shape. The electrode pattern of the second transmission line Lg2 of the first switch circuit SW1 is formed on the fifth layer, the seventh layer to the eleventh layer so as to be coiled.

[0054] The end of the electrode pattern of the first transmission line LL1 formed in the second layer is connected to the electrode pattern of the capacitor C formed in the third layer via a through-hole electrode. The electrode pattern of capacitor C is opposed to the end of the electrode pattern of the second transmission line Lg2 formed in the fifth layer, and constitutes a capacitor. The end of the electrode pattern of the first transmission line LL1 formed on the second layer and the end of the electrode pattern of the second transmission line Lg2 formed on the seventh layer are mounted on the top layer. Is connected to the capacitor Cg6 via a through-hole electrode. With the arrangement of the electrode pattern, the capacitor C is connected in parallel to a part of the first transmission line LL1 and a part of the second transmission line Lg2. Above In the embodiment shown in FIG. 4, the electrode pattern that forms part of the first transmission line LL1, the electrode pattern that forms part of the second transmission line Lg2, and the electrode pattern of the capacitor C are stacked in the stacking direction. It has a part that overlaps.

[0055] Example 1

The high-frequency module shown in Fig. 4 was fabricated using an 11-layer dielectric green sheet made of LTCC that can be fired at low temperatures below 950 ° C. The thickness of the green sheet is preferably 40 to 200 μm so that the transmission line and the capacitor can be easily formed. The electrode pattern is preferably formed of a silver-based conductive paste. Electrode patterns for transmission lines and capacitor are formed on each green sheet, and through holes are provided as appropriate. After lamination, pressure bonding is performed, and firing is performed at 950 ° C. Lamination of approximately 10 mm x approximately 8 mm x approximately 0.65 mm Get the body. A diode, transistor, chip inductor, chip capacitor, resistor, etc. are mounted on the top surface of the laminate to obtain a high-frequency module. A high-frequency module is usually covered with a metal case (not shown) with a height of about 1.6 mm. Instead of a metal case, it may be a resin-sealed package. In this case, the height is about 1.5 mm.

FIG. 5 shows the pass characteristics of the high-frequency module of Example 1, and FIG. 6 shows the pass characteristics of the high-frequency module having a conventional circuit structure. The conventional characteristics have a large rise of about 15 dB in the unnecessary band near 3 GHz. Depending on manufacturing variations, it may exceed about 10 dB, which may cause problems in the reception characteristics. On the other hand, in the high-frequency module of Example 1, the vicinity of 3 GHz can be suppressed to about −25 dB or less, and adverse effects on the reception characteristics are eliminated. In addition, the passage loss of the high-frequency module of Example 1 is about 1.0 dB, which is about the same as the conventional high-frequency module that does not include a capacitor for suppressing unnecessary waves.

[0057] [2] Second embodiment

(A) Demultiplexer circuit

FIG. 7 shows an equivalent circuit of the branching circuit according to the second embodiment of the present invention. The demultiplexing circuit passes the transmission signal of the high frequency side transmission circuit or the low frequency side transmission circuit during transmission, demultiplexes signals having different frequencies during reception, and sends the reception signal to the high frequency side reception circuit or low frequency side reception circuit. Has the function of distributing. Diagram consisting of low frequency filter and high frequency filter 7 includes a common terminal Pc, a low frequency terminal PI, and a high frequency terminal Ph. The high-frequency filter includes a first capacitor CH4 connected to the common terminal Pc, a second capacitor CH5 connected between the first capacitor CH4 and the high-frequency terminal Ph, the first capacitor CH4, and the first capacitor CH4. A series resonance circuit including a first transmission line LH4 and a third capacitor CH6 connected between a connection point of the second capacitor CH5 and the ground. The low-frequency filter has one end connected between the second transmission line LL1 provided between the low-frequency terminal P1 and the common terminal Pc, and between the second transmission line LL1 and the low-frequency terminal P1. A series resonance circuit including a third transmission line LL2 and a fourth capacitor CL1 whose ends are grounded. The circuit configuration of the branching circuit, such as the low-pass filter, is not limited to that described above, and can be changed as appropriate.

In the branching circuit, the first transmission line LH4, the first capacitor CH4, the second capacitor CH5, and the third capacitor CH6 are configured by electrode patterns formed in a dielectric layer constituting the multilayer body. The In the stacked body in which the dielectric layers 7 are stacked, the electrode 5 connected to the common terminal Pc among the counter electrodes constituting the first capacitor C H4 is opposed to the ground electrode as shown in FIG. Thus, parasitic capacitance can be generated using the electrode of the capacitor that is a part of the branching circuit. In the configuration of FIG. 9, the electrode 5 and the ground electrode 6 constituting the first capacitor CH4 face each other on both sides of one dielectric layer. The magnitude of the parasitic capacitance can be easily controlled by adjusting the thickness of the dielectric layer, the area of the ground electrode 6, and Z or the dielectric constant of the dielectric layer. The other electrode of the first capacitor CH4 and the electrode of the second capacitor CH5 (on the side of the first capacitor CH4) are formed as the common electrode 4 above the electrode 5 in the laminate. The other electrode 3 (connected to the high frequency terminal Ph) of the second capacitor CH5 is formed above the common electrode 4. Thus, the electrode 5 and the common electrode 4 constitute the first capacitor CH4, the common electrode 4 and the electrode 3 constitute the second capacitor CH5, and a parasitic capacitance is generated between the ground electrode 6 and the electrode 5. . Conventionally, parasitic capacitance is not generated in the high-pass filter part as much as possible (for example, Japanese Patent Application Laid-Open No. 2002-26677), but in the present invention, this is also used positively from the viewpoint of harmonic suppression. When a demultiplexing circuit is used for the antenna switch module, as shown in Fig. 8, parasitic capacitance Cp is attached to the antenna and suppresses harmonics. [0059] (B) High frequency circuit

The high-frequency circuit having the branching circuit includes a first switch circuit that switches between a transmission system and a reception system in the first frequency band on the low frequency side divided by the branching circuit, and a high-frequency side divided by the branching circuit. A second switch circuit for switching between a transmission system and a reception system in the second frequency band; As an equivalent circuit of the high-frequency circuit of this embodiment, FIG. 10 shows the low-frequency GSM850 band (transmission frequency: 824 to 849 MHz, reception frequency: 869 to 894 MHz) and the EGSM band (transmission frequency: 880 to 915). MHz, reception frequency: 925 to 960 MHz), high frequency DCS band (transmission frequency: 1710 to 1785 MHz, reception frequency: 1805 to 1880 MHz) and PCS band (transmission frequency: 1850 to 1910 MHz, reception frequency: 1930 Fig. 11 shows the equivalent circuit of a quad-band antenna switch circuit using (~ 1990 MHz). Since this equivalent circuit is the same as the equivalent circuit of the first embodiment except that the branching circuit of the second embodiment is used, the description thereof is omitted.

(C) High frequency module

FIG. 12 shows a high-frequency switch module in which the antenna switch circuit shown in FIG. 10 is formed on a multilayer substrate. In the sixth layer, a ground electrode is formed on almost the entire surface except the region where the through-hole electrode is formed. The first and second capacitors CH4 and CH5 of the high frequency filter of the branching circuit are provided below the sixth layer provided with the ground electrode. Specifically, the electrode 3 (high frequency terminal Ph side) of the second capacitor CH5 is formed on the ninth layer, the common electrode 4 of the first and second capacitors CH4 and CH5 is formed on the tenth layer, The electrode 5 (common terminal Pc side) of one capacitor CH4 is formed on the eleventh layer, and the electrode 5 faces the ground electrode formed on the back surface of the laminate. Electrodes 3, 4 and 5 are also facing each other. In this embodiment, the force that generates the parasitic capacitance by using the opposite of the ground electrode formed on the back surface is not limited to this, and the ground electrode in the stacked body may be used.

[0060] When using individual components such as chip capacitors and chip inductors in the branching circuit, a ground electrode is provided directly below the mounting pad having the same potential as the antenna terminal (common terminal Pc), or a ground is provided around the mounting node. Parasitic capacitance may be generated by arranging electrodes. Further, in order to add a parasitic capacitance to the antenna terminal, a mode in which a duplexer is not connected to the antenna terminal may be adopted. In either case, insertion loss will deteriorate if the parasitic capacitance is too large. Therefore, it is desirable to adjust the electrode spacing to make the parasitic capacitance about 1 pF or less.

[0061] Example 2

A laminated module having the structure shown in Fig. 12 was produced as an antenna switch module. The laminated module shown in Fig. 12 was also formed with a high-frequency amplifier. The laminated module is composed of dielectric green sheets of the first to eleventh layers, and BOTTOM indicates the back side of the laminated body. The dielectric green sheet used in this example is an LTCC that can be fired at a low temperature of 950 ° C or lower. The dimensions and manufacturing method of the laminate are the same as in Example 1.

[0062] When the branching circuit of Example 2 was compared with the conventional branching circuit in which the electrode of the first capacitor CH4 (connected to the common terminal Pc) was not opposed to the Dutch electrode, the insertion loss was almost the same. The same amount of force attenuation has been greatly improved by about 1.5 to 7 dB on the low frequency side (GSM and EGSM), and greatly improved by about 1.5 to 3 dB on the high frequency side (DCS and PCS). .

As the high-frequency switch module having the branching circuit of Example 2, the laminated module shown in FIG. 12 was produced. The thickness of the dielectric that forms the main capacitor of the demultiplexing circuit is 25 m, and the distance between the counter electrode of the first capacitor CH4 and the ground electrode on the back surface is 100 μm. Was adjusted to about 0.5 pF. When the high-frequency switch module of Example 2 was compared with a high-frequency switch module having a conventional branching circuit, the insertion loss was equivalent, but the attenuation was greatly improved to about 2 to 7 dB on the low-frequency side. On the high frequency side (DCS and PCS), it was found that there was a significant improvement of about 1.5 to 14 dB.

[0064] [3] Third embodiment

The high-frequency module according to the third embodiment is different from the first embodiment except for the arrangement of the transmission lines LL1, LL2, LH4, Lgl, Lg2, and Ld2 included in the branching circuit Dip and the first and second switch circuits. The same. Ldl is a transmission line through which harmonics in the second frequency band pass. Signals in the first frequency band on the low frequency side pass through transmission lines LL1, LH4, and Lg2, and signals in the second frequency band on the high frequency side pass through transmission lines LL2, Lgl, and Ld2. Transmission lines LL 2 and Lgl are circuit elements on the low frequency side, but the high frequency side component leaked to the low frequency side circuit passes, and transmission line LH4 is a circuit element on the low frequency side but leaked to the high frequency side circuit. Low frequency component passes. [0065] A transmission line through which a signal of the first frequency band passes in order to suppress mutual interference between the transmission and reception circuits of the first frequency band (GSM850 and EGSM) and the second frequency band (DCS and PCS) LL1, LH4, and Lg2 are provided on one side in the stacking direction of the ground electrodes in the stack, and transmission lines LL2, Lgl, and Ld2 through which signals in the second frequency band pass are provided on the other side in the stacking direction of the ground electrodes. That is, the transmission line is separated in the stacking direction by the ground electrode. The second harmonic of the first frequency band, GSM850 and EGSM, is almost the same as the frequency band of the second frequency band, DCS and PCS, so the second harmonic of the first frequency band is the second frequency band. The influence on the frequency band is large. The above configuration is particularly effective in the case of such a relationship between the first frequency band and the second frequency band. The ground electrode is formed on the dielectric layer so as to at least partially separate the transmission line through which the signal in the first frequency band passes and the transmission line through which the signal in the second frequency band passes! However, it is preferred that the dielectric layer be formed wider than both transmission lines so that they are completely separated. Another ground electrode may be formed between the electrode pattern of the transmission line through which the signal of the first frequency band passes or between the electrode pattern of the transmission line through which the signal of the second frequency band passes. . It is preferable to connect the ground electrodes provided in multiple layers with through-hole electrodes. ,.

FIG. 13 shows a high-frequency module in which the antenna switch circuit shown in FIG. 10 is formed in a laminate. An antenna switch circuit is formed in the area 1 of about 1/3 on the right side of each layer, and a high-frequency amplifier circuit is formed in the area 2 of about 2/3 on the left side. The high-frequency amplifier circuit is connected to, for example, the GSMZEGSM transmission terminal Tx-LB of the antenna switch circuit in FIG. 10, and sends the amplified transmission signal to the antenna switch circuit. It is preferable to connect the high-frequency amplifier and the antenna switch circuit on the upper layer side, and to avoid mutual interference, the high-frequency amplifier line and the antenna switch circuit line should be formed in different layers so as not to overlap each other.

FIG. 13 shows, in order from the upper left, the eleven dielectric layers on which electrode patterns are formed and the back surface BOTTOM of the laminate. In the sixth layer, a ground electrode is formed on almost the entire surface except the region where the through-hole electrode is formed. The transmission lines LL1, LH4, and Lg2 through which signals in the first frequency band pass are formed on the second to fifth layers above the sixth layer with the ground electrode. Forces formed Transmission lines LL2, Ld2, Lgl through which signals in the second frequency band pass are formed on the 7th to 11th layers below the 6th layer where the ground electrode is provided. ing. Of the transmission line and capacitor electrode patterns constituting the low-pass filters LPF1 and LPF2 used in the transmission system of the first and second frequency bands, the electrode pattern of the transmission line is provided above the ground electrode, The electrode pattern of the capacitor is provided on the lower side of the ground electrode.

[0068] Example 3

A laminated module shown in FIG. 13 was produced as an antenna switch module. An 11-layer dielectric green sheet made of LTCC that can be fired at a low temperature of 950 ° C or lower was laminated under the same conditions as in the first embodiment. In all layers constituting the laminated module, the electrode pattern constituting the antenna switch circuit was formed in the right region 1 and the electrode pattern constituting the high-frequency amplifier was formed in the left region 2.

[0069] The conventional high-frequency module is separated from the high-frequency module of Example 3, the transmission line through which the signal in the first frequency band passes and the transmission line through which the signal in the second frequency band passes in the stacking direction. When the transmission side is compared, the insertion loss is greatly improved to about 0.1 to 0.2 dB on the low frequency side (GSM and EGSM), and is greatly improved to about 0.05 to 0.2 dB on the high frequency side (DCS and PCS). The amount of attenuation was greatly improved to about 3 to 12 dB on the low frequency side, and about 5 to 15 dB on the high frequency side (DC S and PCS). On the receiving side, the insertion loss was greatly improved by about 0.05 to 0.1 dB on the low frequency side (GSM and EGSM), and greatly improved by about 0.1 to 0.3 dB on the high frequency side (DCS and PCS). Since the leakage of radio waves is greater at higher frequencies! /, The effect of the present invention is greater at higher frequencies.

[0070] Characteristic deterioration in an unnecessary band considered to be due to interference was also eliminated. This effect can be clearly confirmed from the isolation characteristics between the reception (passage characteristics between the low-frequency receiving terminal and the high-frequency receiving terminal). The isolation improvement effect was about 5 dB in the low frequency band, about 2 dB in the high frequency band, and about 3 to 20 dB in each nth harmonic band. The effect of improving the insertion loss and attenuation is considered to be due to the shielding effect on the low frequency side and the high frequency side. When a GaAs switch is used, the same effect can be obtained by separating the low frequency side line and the high frequency side line with a ground electrode. [4] Fourth embodiment

The low-pass filter suitable for the high-frequency circuit and high-frequency module of the present invention will be described in detail below. Fig. 10 shows an example of an equivalent circuit of a quad-band antenna switch circuit covering GSM and EGSM in the low frequency band and DCS and PCS in the high frequency band, and Fig. 14 shows each dielectric layer constituting the laminate incorporating the low-pass filter. The upper electrode pattern is shown. Since parts other than the low-pass filter of the antenna switch circuit are the same as those of the first embodiment, their description is omitted.

[0071] The low-pass filter may be a single laminated low-pass filter. The configuration of the laminated module using the low-pass filter is not particularly limited, but is preferably an antenna switch module or a composite module of an antenna switch circuit and a high-frequency amplifier circuit.

[0072] The first and second low-pass filters LPFl and LPF2 shown in FIGS. 10 and 11 may have the same configuration. FIG. 15 shows an equivalent circuit of the low-pass filter LPF (LPF1 or LPF2). The first low-pass filter LPF1 is an L-type low-pass filter that also includes a transmission line LL3 and capacitors CL2 and CL3 that form an inductance. Capacitor CL3 is connected in parallel with transmission line LL3 to form a parallel resonant circuit. The configuration of the low-pass filter is not limited to that shown in FIG. 15, but may be, for example, a π-type low-pass filter shown in FIG.

[0073] The first low-pass filter LPF1 in the multilayer body will be described with reference to FIG. 14 showing the eleven dielectric layers on which the electrode patterns are formed and the back surface BOTTOM of the multilayer body. FIG. 14 shows the first to eleventh layers and the back surface in order of the upper left force. The transmission line LL3 composing the low-pass filter LPF1 and the electrode patterns composing the capacitors CL2 and CL3 are also indicated by LL3, CL2 and CL3, respectively. A ground electrode G1 is formed on the sixth layer, and a transmission line electrode pattern LL3 is formed on the second to fifth layers above the ground electrode G beam. Capacitor electrode patterns CL2 and CL3 are formed on the ninth to eleventh layers below the ground electrode G1. That is, the plurality of capacitor electrode patterns CL2 and CL3 and the transmission line electrode pattern LL3 constituting the first low-pass filter LPF1 are separated in the stacking direction by the ground electrode G1. Both electrode patterns are preferably separated on the entire surface by the ground electrode G1. Similarly, when the low-pass filter has a plurality of transmission lines, the electrode patterns constituting the plurality of transmission lines are collectively formed on one side of the ground electrode in the stacking direction. [0074] In order to reduce the size of the multilayer body, in the configuration shown in FIG. 14, the transmission line electrode pattern LL3 and the capacitor electrode patterns CL2 and CL3 overlap in the stacking direction. In the lowpass filter of the present invention, the transmission line and the capacitor are separated by the ground electrode, so there is no mutual interference even if the inductor and the capacitor overlap in the stacking direction. The first layer, etc., outside the transmission line LL3 is provided with a ground electrode that overlaps the transmission line electrode pattern LL3 in the stacking direction, so that a ground electrode facing outside the transmission line LL3 is arranged. It is possible to avoid the formation of parasitic capacitance and the increase in insertion loss.

In the configuration shown in FIG. 14, the ground electrode G1 and another ground electrode (counter ground electrode of the capacitor CL2) are provided on the capacitor electrode patterns CL2 and CL3 side. In this case, the ground electrode G1 sandwiched between the transmission line electrode pattern LL3 and the capacitor electrode patterns CL2 and CL3 may or may not function as the opposing ground electrode of the capacitors CL2 and CL3. The ground electrode G1 sandwiched between the transmission line electrode pattern LL3 and the capacitor electrode patterns CL2 and CL3 and the opposing ground electrode of the capacitors CL2 and CL3 may be constituted by a single ground electrode. In this case, a ground electrode different from the ground electrode G1 is not provided outside the capacitor electrode patterns CL2 and CL3. This configuration is advantageous for downsizing.

[0076] In the low-pass filter disclosed in Japanese Patent Application Laid-Open No. 11-27177, since the ground electrode is partially formed between the inductance and the capacitor, the electrode pattern for inductance and the electrode pattern for capacitor are not completely separated. However, the low-pass filter according to the present embodiment is largely different in that a ground electrode exists between the inductance electrode pattern and the capacitor electrode pattern. Furthermore, since there is no other opposing ground electrode outside the transmission line electrode pattern, the formation of parasitic capacitance of the transmission line functioning as an inductance is suppressed, contributing to loss reduction.

In the low-pass filter shown in FIG. 17 (a), a ground electrode 14 is provided between a transmission line electrode pattern 13 and a capacitor electrode pattern 15 that form an inductance in the stacking direction. A ground electrode 16 is provided below 15. The ground electrode 14 is disposed in a region where the transmission line electrode pattern 13 and the capacitor electrode pattern 15 are opposed to each other in the stacking direction in which the ground area is larger than the transmission line electrode pattern 13 and the capacitor electrode pattern 15 provided above and below the ground electrode 14. Ground electricity throughout Since the pole 14 is present, the ground electrode 14 prevents interference between the transmission line and the capacitor.

[0078] Since the ground electrode is not provided on the upper side of the transmission line electrode pattern 13, no parasitic capacitance is formed on the upper side of the transmission line. In this case, as long as the impedance design allows, by increasing the distance between the transmission line forming the inductance and the ground electrode, it is possible to suppress the parasitic capacitance generated below the transmission line, thereby reducing the insertion loss. . When the ground electrode 14 is not used as one of the counter electrodes of the capacitor, it is preferable to increase the distance between the electrode pattern on the ground electrode 14 side of the electrode pattern of the transmission line and the ground electrode to suppress the generation of parasitic capacitance. However, this does not apply when the ground electrode 14 is used as one of the counter electrodes of the capacitor.

In the configuration shown in FIG. 17 (b), a force capacitor electrode pattern in which a ground electrode 14 is provided between a transmission line electrode pattern 13 and a capacitor electrode pattern 15 forming an inductor in the stacking direction. No other ground electrode is provided below 15, and the ground electrode 14 is used as the counter electrode of the capacitor. With this configuration, the same effect as the configuration shown in FIG. 17 (a) can be obtained. In this configuration, since the ground electrode 14 is used as one of the counter electrodes, the distance between the electrode pattern 15 and the ground electrode 14 is preferably set to 50 m or less.

The second low-pass filter shown in FIG. 10 can also be configured in the same manner as the first low-pass filter. When the laminated module includes a plurality of low-pass filters as described above, the ground electrodes of the plurality of low-pass filters are not necessarily formed on the same dielectric layer, but are preferably formed on the same dielectric layer. Such a configuration is effective in reducing the size of the stacked body and suppressing unnecessary stray capacitance.

[0081] The low-pass filter can be used in any of the antenna switch circuits of the first to third embodiments, and is not limited to the high-frequency module according to the first and second embodiments, but other multiband high-frequency filters. Can be widely used for modules.

[0082] Example 4

As an antenna switch module, the laminated module shown in Fig. 14 was fabricated using an 11-layer dielectric green sheet made of LTCC that can be fired at a low temperature of 950 ° C or lower. The stack module also has a high frequency amplifier. The dimensions and manufacturing method of the laminate are the first implementation. The form is the same.

[0083] When the low-pass filter of Example 4 was compared with the conventional low-pass filter having the ground electrode above the transmission line forming the inductance, the insertion loss was about 0.3 on the low-frequency side (GS M and EGSM). Greatly improved to ˜0.35 dB, greatly improved by about 0.2 to 0.3 dB on the high frequency side (DCS and PCS), and greatly improved to about 2 to 5 dB on the low frequency side (GSM and EGSM) A significant improvement of about 4 to 10 dB on the high frequency side (DCS and PCS) was a major factor. This is because the parasitic capacitance of the transmission line that forms the inductance is reduced, and the transmission line is shorter than the conventional design. The same improvement effect was obtained when the low-pass filter was incorporated in the high-frequency switch module.

[0084] Since the insertion loss deteriorates when the parasitic capacitance of the transmission line is large, it is preferable to set the distance between the electrode of the transmission line and the Darling electrode as wide as possible. It was adjusted. On the other hand, in the prototype circuit configuration, if the parasitic capacitance on the capacitor side is large, it becomes difficult to design the impedance to 50 Ω, and matching between the low-pass filter and other circuits becomes difficult. The distance was adjusted to 225 m for the prototype module, which is preferably set as wide as possible.

[0085] When the low-pass filter of Example 4 was compared with the conventional low-pass filter having no intermediate ground electrode, the insertion loss was greatly improved to about 0.2 to 0.3 dB on the low frequency side (GSM and EGSM). The high frequency side (DCS and PCS) is greatly improved to about 0.2 to 0.3 dB, and the attenuation is greatly improved to about 5 to 8 dB on the low frequency side (GSM and EGSM). The major improvement was about 5 to 12 dB. In addition, the low-pass and high-frequency attenuation poles did not appear clearly in the conventional low-pass filter, and it was difficult to design the low-pass filter. However, the designed low-pass filter clearly shows the designed attenuation pole and is thought to be due to interference. The characteristic deterioration in the unnecessary band is eliminated. Thus, the design for obtaining the desired characteristics has become simple and the design time has been shortened. Furthermore, when a high-frequency switch module was used, it had the same improvement performance.

[0086] When the ground electrode arranged in the middle of the low-pass filter of the present invention is used as a grounded counter electrode of the low-pass filter, various characteristics are improved in the same manner as described above, and the thickness of the laminate can be reduced by about 100 m. Miniaturization is possible. Of course, this effect is a laminated module Can also be obtained.

[0087] Except in the case where the transmission line of the switch circuit is an indispensable configuration, the first and second switch circuits SW1, SW2 are also used as the first and second switch circuits SW1, SW2, for example, SPDT (single pole double throw type) ) GaAs switches such as switches can also be used. The use of GaAs switches reduces the number of transmission lines used in the switch. In addition, the arrangement of the branching circuit in the high frequency circuit is not limited to the position shown in the figure. For example, the common terminal of the switch circuits SW1 and SW2 is connected to the antenna ANT, and the branching circuit is connected to the transmission side terminal and the reception side terminal of the switch circuit. It is also possible to connect another circuit between the antenna ANT and the demultiplexing circuit. Furthermore, the branching circuit may be replaced with an SPnT switch (n is a natural number of 2 or more) to switch between frequency band and transmission / reception.

The present invention is not limited to the above embodiment, and can be applied to various multiband high frequency modules.

[0089] The dielectric layer used in the high-frequency module of the present invention can be formed of ceramic or resin. When the resin is used as a substrate, an element that cannot be formed with an electrode pattern on a multilayer substrate such as a capacitor may be a chip element mounted on the substrate.

Claims

The scope of the claims

[1] A common terminal, a low frequency terminal, a high frequency terminal, a low frequency side path having a low frequency filter provided between the common terminal and the low frequency terminal, the common terminal and the high frequency A branching circuit having a high-frequency side path having a high-frequency filter provided between the terminal and the low-frequency filter, the first transmission line connected in series to the low-frequency side path; A branching circuit comprising a capacitor connected in parallel to a part of the first transmission line.

[2] In the branching circuit according to claim 1, the capacitor is connected in parallel to a part on the low frequency terminal side of the first transmission line to form a parallel resonance circuit, and the first transmission line A part other than the part constitutes an inductance part.

[3] a common terminal, a low frequency terminal, a high frequency terminal, a low frequency side path having a low frequency filter provided between the common terminal and the low frequency terminal, the common terminal and the high frequency A demultiplexing circuit including a high-frequency side path having a high-frequency filter provided between the terminals, wherein the parasitic capacitance formed on the common terminal side is used as a capacitor for suppressing unnecessary waves. Demultiplexing circuit.

[4] The branching circuit according to claim 3, wherein the high frequency filter includes a first capacitor connected to the common terminal, and the parasitic capacitor is formed on the common terminal side of the first capacitor. A demultiplexer circuit characterized by having

[5] The branching circuit according to claim 4, wherein an electrode connected to the common terminal and a ground electrode among the counter electrodes constituting the first capacitor are arranged to face each other, so that both electrodes A branching circuit having the parasitic capacitance formed therebetween.

[6] In the branching circuit according to claim 4, the high frequency filter includes a first capacitor connected to the common terminal, and a first capacitor connected between the first capacitor and the high frequency terminal. A second resonance capacitor, a third transmission line connected between the first capacitor and the second capacitor, and a ground, and a series resonance circuit consisting of a third capacitor. The three transmission lines, the first capacitor, the second capacitor, and the third capacitor are configured in a stacked body formed by stacking dielectric layers on which electrode patterns are formed. Opposing the first capacitor A branching circuit characterized in that an electrode connected to the common terminal among the electrodes faces a ground electrode.

[7] A high-frequency circuit comprising the branching circuit according to claim 1 or 2, further comprising a second transmission line connected to the low-frequency terminal, wherein the capacitor is a part of the first transmission line. And a high-frequency circuit connected in parallel to at least a part of the second transmission line.

[8] The high-frequency circuit according to claim 7, further comprising a switch circuit that is connected to the low-frequency terminal and performs switching between a transmission-side path and a reception-side path of the low-frequency side path, and the second transmission A high-frequency circuit characterized in that the line is a transmission line provided in a receiving-side path of the switch circuit.

[9] A high-frequency module, wherein the branching circuit according to claim 1 or 2 is configured on a multilayer substrate formed by laminating dielectric layers on which electrode patterns are formed.

[10] A high-frequency module according to claim 7 or 8, wherein the high-frequency circuit is configured on a multilayer substrate formed by stacking dielectric layers on which electrode patterns are formed.

[11] The high-frequency module according to claim 10, wherein an electrode pattern constituting a part of the first transmission line, an electrode pattern constituting at least a part of the second transmission line, and the capacitor A high-frequency module, characterized in that the electrode pattern overlaps in the stacking direction of the stack.

[12] A high-frequency module comprising a multi-layer substrate formed by laminating dielectric layers on which the branch circuit power electrode pattern according to any one of claims 3 to 6 is formed.

[13] The high-frequency module according to claim 12, wherein the first switch circuit that switches between the transmission system and the reception system in the first frequency band divided by the branching circuit, and the second switch that is divided by the branching circuit. A high-frequency module comprising: a second switch circuit that switches between a transmission system and a reception system in the frequency band.

[14] A high-frequency module used in a multiband wireless communication apparatus that selectively uses at least a first frequency band and a second frequency band higher than the first frequency band, In one transmission / reception system and the second frequency band. A demultiplexing circuit that separates the second transmission / reception system, a first switch circuit that is connected to the demultiplexing circuit and switches between the transmission system and the reception system of the first transmission / reception system, and is connected to the demultiplexing circuit A second switch circuit for switching between the transmission system and the reception system of the second transmission / reception system,

The branching circuit, the first switch circuit, and the second switch circuit are each configured as a laminate formed by laminating dielectric layers on which electrode patterns are formed,

Of the transmission lines of the branching circuit, the first switch circuit, and the second switch circuit, the transmission line through which the signal of the first frequency band passes is provided in the dielectric layer in the laminate. Formed on one side of the ground electrode in the stacking direction, and the transmission line through which the second frequency band signal passes is formed on the other side of the ground electrode in the stacking direction! High frequency module.

15. The high frequency module according to claim 14, wherein the second frequency band and a frequency band of a second harmonic of the first frequency band are substantially the same.

[16] The high-frequency module according to claim 14, wherein the dielectric layer includes a low-pass filter including a transmission line that forms an inductance and a capacitor, and the electrode layer that forms the transmission line is formed. A dielectric electrode separated from the dielectric layer on which the electrode pattern constituting the capacitor is formed by a ground electrode in the stacking direction, and facing the opposite side of the ground electrode in the stacking direction with respect to the electrode pattern forming the transmission line. The high frequency module characterized by not having.

17. The high-frequency module according to claim 16, further comprising a ground electrode facing the opposite side of the ground electrode in the stacking direction with respect to the electrode pattern constituting the capacitor.

18. The high-frequency module according to claim 17, comprising a plurality of the capacitors.

19. The high frequency module according to claim 17, wherein at least one of the capacitors is connected in parallel to the transmission line.